Towing machine and method of towing



A. CUNNINGHAM. TOWING MACHINE AND METHOD OF TOWING.

APPLICATION FILED NOV- 22, 1920. 1,414,724. Patented May2,1922.

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A. CUNNINGHAM. TOWING MACHINE AND METHOD OF TOWING.

APPLICATION FILED NOV. 22, 1920. I

Inventor fillazz ('zzzzzzzkzylzm A. CUNNINGHAM TOWING MACHINE AND METHOD OF TOWING.

I APPLICATION FILED NOV. 22, I920. v I 1,414,724. I Patented May 2,1922.

3 SHEEIS-SHEET 3.

lnvezzlaz .19 1 lam ('aazzz'zzylzam Ms KA firmme s star's ALLAN CUNNINGHAM, 0F SEATTLE, WASHINGTOIhT.

TOWING MACHINE AND METHOD OI? TOWING.

I Specification of Letters Patent.

Patented may a, 11922.

I Application filed November 22, 1920. Serial-No. 425,657.

To all 20710225 it may concern:

Be it known that LALLAN CCXNINGHAM, a subject of the King of England. and residentof the city of Seattle. in the county of lxing and State of Washington, have invent ed certain new and useful Improvements in Towing Machines and-Methods of Towing. of which the following is a specification.

My invention relates to a method of and apparatus for use in towing vessels. It con: sists in a methodwh'ereby the towing'pull or torque is opposed by an electrically produced torque and. whereby this electrically produced torque is varied by andin accordance withthe variations occurring in the towing torque. p

It further consists in apparatus whereby the above results are secured. It is the object of my invention to provide a method and means whereby the constantly varying pull of a towing line may be satisfactorily taken care of and handled by electrical apparatus.

Another object of my invention is to provide simple, etticient, and convenient forms of apparatus for carrying out my method,

. which will be economical in power consumed, and sensitive to control in operation. My invention comprises those novel steps and combinations thereof constituting an improved method of towing, and also those novel parts and combinations thereof which constitute my improved apparatus.

In the accompanying drawings I have illustrated more orless diagrammatically several arrangements for carrying out my improved method.

Figure 1 represents one arrangement,"

which is the one it most prefer.

Figure 2 represents the electrical diagram of this form of apparatus.

Figure 3 represents an alternative arrangement of parts.

Figure 4 represent the electrical diagram for this alternative apparatus. Figure 5 represents a third form of apparatus. I

In the form, of construction shown in Figures 1 and 2, the towing line 10 is wrapped about a drum. capstan, or winch 1 which isrotatably mounted. An electric. motor 2 is connected to the drum 1 torot-ate the same. Current is supplied to the motor 2 from any suitable source throu h the circuit 20. The source which I have s iown in these figures is a generator 3; This generator is preferably t2. from thedrum 1.

separately excited through the excitingcircuit '30, and may be rotated by any suit-' able means acting upon the pulley"3l.

In the exciting circuit 30 of the generator I provide one or more variable resistance members shown herein as the rheostats 4 and 5. The rheostat 5 is manually controllable through a suitable handle] :51 to set the initial-resistance in the field circuit at any given amount. The rheostat 4: has its. con-' tact arm. 41 connected to be moved,or,ro tated, relative to the fixed contact members I This may be done through suitable gearing, illustrated tit-4:3. By thus connecting the drum and the rheostat -l, means are provided for varying the field resistance accordingto the direction and amount by which the drum is rotated.

at" switch" SEQ-adapted to bridge the rheos" stat i may be employed to cut out thisrheostat whenever -.it is desired to operate the drum free from automatic control. der to facilitate paying out theline I may provide a reversing switch 21 in connection with the motor 2. i I may further provide a brake, indicated at 11. which is electrically controlled through apparatus so connected as to be inoperative while the motor circuit is closed and current is flowing. but which will be included in the motor circuit and'become operative whenever the current is shut ofi,

thereby acting to hold the drum 1 in any given position if and when the drum-controlling motor is cut out.

The generator 3 should be capable of pro-' ducing a current which. when applied to the drum motor 2, willlproduce a torque in the drum equal to the maximum torque produced therein by the towline. Thedelivery In orof this current to the drum motor is, however, controlled so that normally much less than the maximum output is received by the motor 2. i I

The rheostat, or whatever controlling means are employed. is adjusted so that at a certain basic or normal pull upon the tow line, the torque of the motor acting upon the drum exactly balancesthe pull of the tow line. and so that as the pull upon the line becomes greater oiless than this basic pull, the paying outand taking up of the tow line by the drum changes the amount of current l'eceit'ed by the motor 2 and therefore the torque communicated to the drum, this torque decreasing as the line is taken in and inereasmgesrt Is paldeutl" The aunt of current supplied by the generator .3 is controlled by cutting in more or less resistance in the generator field circuit 30. The initial or basic motor torque which counter-- balances the towing torque may-be set for any given tow line pull by means of the manually operable rheostat 5.

An increase or decrease 1n the towing torque will produce movement of the drum. If the towing torque is increased, line will ;be paid out, and if it is decreased slack will be taken .up, for thereason that the equilibrium between the motor torque and the towing-torque is disturbed, However, such motion of. the drum is communicated to the automatic rheostat 4. An increase in the towing torque rotates the contactmember 41 of the rheostat 4 to lessen the field resistance of, the"generator" 3 and in this manner the current supplied to the motor, and hence the motor torque, is increased in proportion and opposite in efl'ect to the variation from normal of the towing torque. A Line will be paid.

out until the increase in the motor torque overcomes the increase in the ,towingtorque when the motor 2 will cause the drum lto be reversed and the line paid out will again be taken in until the tow and tug have resumed their normal relative positions. 30

Assisting the variation in field resistance caused by the action of the rheostat 4' in producing the extra motor torque required to counter-balance the extra towing torque, is the E. M. F.'produced in the motor by rotation against the current. This will turn the motor into a generator for the time being,

' and will produce a tendency to rotate in the direction opposite tothe direction in which it 1s turned by the towing torque. In other words, the motion of the motor armature produces an E. M. F. in the circuit 20 in the Eli same direction as that from the generator, thus further increasingthe torque resisting the run out of the cable, in proportion to the speed at which it is run out. I As the pullon the towing line 10 decreased, the motor comes to a'standstill, reverses, and begins to wind up the cable paid out due to the increased voltage of the generator, at a speed in pro-' portion to the speed of release of the strain,

until normal or basic position of the drum is reached and parts are in equilibrium.

It will be evident that a sudden slackening of the strain upon the line 10- will first permit the motor to take upthe slaclnthe motor torque for the time being. overcomingthe towing torque. lllowever, as. strain is .gradually. placed upon the line, the two torques will again become equal and, due to the decreased EJM. F. in the motor circuit 20 caused in the manner previously described by such rotation, and by the action ofthe rheostat 4, the line 't'alren upwill again be paid out until the tow and tug again resume their norl relative positions as before,

.line as line having no straln thereon, the automatic The motor which is employed must be of a capacity considerably beyond that required;

to produce the normal motor torque, as it should not require its full load current to produce torque enough to balancethemaximum steady pull on the towing line, as the current required fluctuates and the length of time at a standstill with full current flowing will give more thannormal heating in the" motor. v The generator should'have commutating poles so as to neutralizethe demagnetizing effect of the armature current, which will be of full load order most of the time and also to provide perfect commutation at the lower voltages which will maintained the greater share of the time. The generator shouldbe equal in continuous current carryi'ng capacity to the motor and should have enough power driving it,;at-approx1mate1y constant speed, to pull in the tow at the required speed. Ordinarily though, this amount of power will not be necessary under the. motor 2 through the reversing switch-21, the towing line may be paid out.

The device shown in Figures 3 and 4 oper-' motor 2. may be supwith. suliicient powerto haul in the ates in the samemanner, but the apparatus is somewhat simpler than that described and shown in Figures 1 and 2, and is in some iii-- stances preferable for this reason. In this form of apparatus the drum 1, the motor 2 with its reversing switch 21, the automatic and the manual rheostat 5 and switch 3 2.for cutting out the automatic rheostat, remain vthe same as has been described in connection with "Figure :1. The apparatus is designed,

'rheostat 4 and its connectionto the drum 1, I

howevenior operating directly from direct r 1 current mains supplied with current from any suitable source (not shown) "The rheostats 4- and 5 in this form are in the motor circuit '22 and control the current supplied;

to the motor through dissipating, in resist ance the difference between full voltage and. the amount required to produce a motor torque sufiicient to counter-balance the towing torque. In this form of apparatus, prac-x tically full load current, or sucient power to haul in the load at tullspeed, will be consumed all the time the machinev is in operation. As there is considerable current passingthrough the rheostats d and '5 these rnust be made sufic'iently' heavy to carry this current. They until be considerably heavier tha'n'those rcq%1 ired in the a I 1 a D. a paratus shown in Figural. lnsrorm is a vantageouefbc till .form of this element differs from that I shown in the figures previously described.

The power varying element here, instead of a variable-effect generator or mainline, consists of a heavy-duty storage battery 6 which suppliesa variable amount of power to the motor 2, the amount depending upon certain contact members which are controlled indirectly by therotation' of the drum 1. I prefer that the motor 2 beexternally excited through the circuit bridging the Instead of an automatic rheostat connected to move with the drum, I employ a selective-switch consisting of the bridge member 7 and the individual 'co'ntact members 71.

The bridge member 7 is connected through suitable gearing 72 to be rotated by the drum 1; The individual contact points 71 with which the bridge member 7 selectively contacts, are each connected to its individual contact member 73. These contact members are pivoted by oneend and are connected electrically in the motor circuit 24. They are adapted to be swung to close contact each with its individual contact point 64 which is so connected to the battery 6 as to control a different number of cells from all of the other contact points 64.

Closing of the circuit between the members 73 and 6t is controlled from the selective switch members 7 and 71 by means of electro-magnets 75, which are fixed relative to the fixed points 64, and which act upon a magnetic portion 76 of the member 73.

The current to each of the electro-magnets 75 is controlled through a circuit 74 leading from its individual contact point 71 to the selective switch, through the magnet. 75 to a fixed auxiliary contact point 77. and thence through an auxiliary contact point 78 carried by that swinging member 73 adjacent in the series of contact membersto the member 73 about to be closed, and thence back to the individual contact points 71 through a control battery 79 and the bridge member 7. The purpose of this construction is to prevent closing of the contacts 73, 64 controlling a certain portion of the battery 6 until all of the remainder of such contacts have been opened. Thisprevents short-circuiting of any of the battery cells.

The operation of the device is substantially the same'as that described for the two previous constructions. Rotation of .the

drum 1 rotates the bridge member 7 of the selective switch to control a certain one of the contacts 73, 64, thereby to throw in more or less current ire the battery 6 to. t

a drum, an electric'motor for motor 2, and increase or decrease in the motor torque in conformity with and opposite in effect to the increase in the towing torque.

That I claim as my invention is:

l. Ina towing machine, in combination, a drum, an electric motor for producing a torque upon said drum, a source of current to said motor normally supplying sufficient power to maintain the motor torque in equilibrium with and opposite in effect to the towing torque, and a rheostat mechanically operated by said drum and electrically connected in the circuit to said motor, and operable to vary the power delivered to the motor proportionally to the variation' from normal of the torque upon the drum, and

- opposite in efi'ect.

.a drum, an electric motor for rotating said drum, and means for maintaining the torque of said motor normally in equilibrium with the towingtorque, said means comprising a rheostat electrically-connected to control the current delivered to the motor and connected mechanically to be moved by said drum, said rheostat being operable to vary the .power transmitted to the motor proportionately to the variation from normal of the towing torque upon the drum, and opposite in effect, and a second rheostat in said motor circuit manually operable to control the power delivered to the motor.

3. In a towing machine, in combination, a drum, an electric motor for producing a torque upon'sa-id drum normally equal and {opposite in efi'ect' to the towing torque there upon, and means operable byv movement of the drum for varying the electromotive force,

in said motor to produce an increase or decrease of motor torque counter and equal to the variation from normal of the towing torque.

4. In .a towing machine, in combination, a drum, an electric motor for producing a torque upon said drum normally equal and opposite in'efie'ot to the towing torque thereupon, means operable by movement of the drum for varying the electromotive force in said motor to produce an increase or decrease of motor torque counter and equal to the variation from normal of thetowing torque, and a brake for said drum in series with the motor and operative while the current ofi 5. In a towing machine, in combination, producing a in this manner producing an .llih

torque upon said drum normally equal and.

"a drum,

an electric motor for producing a torque upon said drum normally equal and opposite in efiect to the towing torque thereupon, and, a pair of rheostats in the motor clrcuit, one being operable automatically by movement of the drum to vary the current supplied thereby to vary the motortorque in conformity with and opposite in eflect 8.11 a towing machine,

a drum,

to the variation from normal of the towing torque, the second rheostat being manuallyoperable'to vary the current supplied.

7. In a towing machine, in combination, a

drum, an electric motor for producing a 1 torque, the second rheostat being manually operable to 'vary the-current supplied, and means for cutting out said automatic rheostat.

in combination, an electric motor torque upon said drum normally equal and opposite for producing a I m efl'ect to the towing torque thereupon, and a rheostat m the motor circuit and maria-me operable by movement of the the current supplied, thereby to vary the motor torque in conformity with and opposite in efi'ect tothe variation from normal of the towing torque, and a brake for sea while the current is ofi'.

9. In a towing machine, in combination,

a drum, an electrlomotor for producing a torque upon said drum, and means'directly in the motor "circuit for varying the power delivered to the motor proportionately with and opposite in efi'ect to the variations from normal of the towing torque upon the drum. 10. In a; towing machine, in combination, a drum, an .electric motor for producing a torque upon sa d drum, a source of current v normall supplying suificient' to said motor 7 power to ma1nta1n t e motor torque in equilibrium with the towing torque, and

drum to vary 6. ea drum in series with the motor and. operative means interposed in the electric circuit bevarying the power tween said power sourceand the motor tor.

delivered to .themeter proportionately to the 1 variationfiremmnrmal ofthe towing. torque, and 'oppesitein eflfect.

ton t is 16th day of November 1 920.

si M- a. Seattle, King County, wishi A LAN CUNNINGHAM. 

